How Deep Should Post Footings Be for a Deck

By code, the bottom of a footing must be at least 12 inches deep and below the local frostline

How deep do decking support posts need to be?

In the corners of the marked area, dig out 700mm deep holes for each of the joist support posts. Ideally the holes need to be about 300mm in diameter at the top and 400mm at the bottom.

Should I concrete my deck posts?

A deck post should always be placed on top of footing, not inside concrete because it can break. … When concrete is poured around a deck post in this way, the post will rot due to moisture buildup by the soil.